Web accessibility is essential to create inclusive apps and services, and it's
an integral part of our Symfony Diversity initiative. With much help from an
accessibility expert, Sandra, we have made the Bootstrap 4 from theme
compliant with the WCAG 2.0 standard.

The standard includes rules and guidelines to make content accessible for users
with disabilities, including impaired vision, learning disabilities and limited
movement.

In addition to minor tweaks and fixes, form errors are now rendered inside
the <label> element to make sure there is a strong connection between the
error and its <input>, as required by the WCAG 2.0 standard.

One small problem.
When I want to render form element without label (example render input name as a placeholder). Then invalid input field is rendered in red without error messages - because errors are inside label (which is not rendered).
For this case users will have to implement separate template :(